According to sources in Croatia, the 25-year-old midfielder made the request as Spurs began their pre-season tour in South Africa and after the club rejected Chelsea’s latest offer of £27 million.

Spurs chairman Daniel Levy is adamant that Modric is not for sale at any price but the midfielder is now pushing as hard as he can to leave. He has surprised Spurs with his determination to quit this summer.

One player who is unlikely to encounter much resistance from his club over a move to Stamford Bridge is West Ham’s Scott Parker.

Chelsea manager Andre Villas-Boas is set to make Parker his first signing at Chelsea and is returning to his former club, Porto, to try to acquire Álvaro Pereira for about €20 million (£17.6 million).

Negotiations opened on Wednesday on a season-long loan deal for Parker with West Ham United demanding a £4 million fee and that Chelsea also pay his £65,000-a-week wages in full.

Meanwhile, one of Porto’s key negotiators will arrive in London today to discuss the possibility of Pereira, who can play as a left-back or left-midfielder, being sold. Porto have already lined up a replacement, appearing to have signed Alex Sandro, from Santos, for £8.3 million.

Relations between Villas-Boas and Porto have deteriorated, however, with the Portuguese club’s president Pinto da Costa criticising the 33 year-old on Wednesday, claiming he was “living with Mourinho’s ghost” and was afraid he would fail.

In an interview with the Portuguese newspaper, O Jogo, he said: “In football when you talk about European giants, the measure is not Chelsea. It’s Real Madrid, Barcelona, Manchester United. I told him this would be [Pep] Guardiola’s last season at Barca and that would be the ideal club for him, but he was scared of the comparisons with Mourinho and left.”

The pursuit of Parker was stepped up yesterday with Chelsea expected to offer more than £2 million in loan fees to bring back their former midfielder and compensate for the loss of the injured Michael Essien.

Although West Ham would prefer to sell the 30 year-old following the club’s relegation to the Championship, chairman David Sullivan admitted yesterday that a loan is attractive if they can return to the Premier League next season.

“This has been mooted that we’d loan him out for a year for a substantial fee and then when we get promotion he’d come back to us,” he said. “That sort of deal would appeal to us. We’d want a loan fee as he has substantial value.”

Parker still lives close to Chelsea’s training ground and is friends with many of the club’s players.